suggested 'normal' limits for menstrual parameters in the mid reproductive years

Last reviewed 05/2019

Suggested normal limits for the four main clinical dimensions of menstruation and the menstrual cycle are (1):

clinical dimensions of menstruation and menstrual cycle Descriptive terms normal limits (5th-95th centiles)
Frequency of menses (days) frequent <24
normal 24-38
infrequent >38
regularity of menses (cycle-to-cycle variation over 12 months; in days) absent  
regular Variation +/-2 to 20 days
irregular Variation > 20 days
duration of flow (days) prolonged >8
normal 4.5-8
shortened <4.5
volume of monthly blood loss (ml) heavy >80
normal 5-80
  light <5


  • 1. Peter Joseph O'Donovan, Charles E Miller. Modern Management of Abnormal Uterine Bleeding (2008)